The present invention relates in general to an apparatus and method for manufacturing a three-dimensional object. More particularly, the apparatus and method is related to freeform fabrication techniques utilizing a planar deposition system having an adjustable planar nozzle. The apparatus and method of the present invention are especially useful in the fields of rapid prototyping and rapid fabrication.
Freeform fabrication techniques are particularly useful for reducing the design, production and maintenance cycle times associated with the manufacture of three-dimensional objects. In the design phase, freeform fabrication techniques are especially useful for prototyping design concepts, investigating inconsistencies in the design and modifying the design prior to full-scale production. In addition, freeform fabrication techniques have been shown to produce higher quality products at lower cost.
However, the need presently exists for improved freeform fabrication techniques capable of producing complex structures at low cost with minimum set-up and run-time. Many recent techniques, especially in the area of complex metal or ceramic tools, have been-developed but remain mostly inadequate. See e.g. J. J. Beaman, N. W. Barlow, D. L. Bourell, R. H. Crawford, H. L. Marcus and K. P. McAlea, xe2x80x9cSolid Freeform Fabrication: A New Direction in Manufacturing,xe2x80x9d ch. 1 (Clair Academic, Boston, Mass. 1997).
The most widely known conventional freeform fabrication system is selective laser sintering (xe2x80x9cSLSxe2x80x9d) as described by D. L. Bourell, H. L. Marcus, N. W. Barlow, J. J. Beaman and C. R. Deckard in U.S. Pat. No. 5,076,869 entitled xe2x80x9cMultiple Material Systemsfor Selective Beam Sintering,xe2x80x9d which issued in 1991. This method employs a heat laser to fuse or xe2x80x9csinterxe2x80x9d selected areas of powdered material such as metal or ceramics. In practice, a vat of powder is scanned by the laser, thereby melting individual particles that in turn stick to adjacent particles. The sintered layer, which is attached to a platform, is lowered into the vat, and new layers are deposited and sintered on top of the previous layers until the entire three-dimensional object or part is produced. An advantage of the sintering method is that the non-heated powder serves as a support for the part as it is formed. Consequently, the non-heated powder can be shaken, dusted or otherwise removed from the resulting object.
Conventional selective laser sintering systems, however, require the use of complex and expensive optical systems where the resolution and level of detail of the final product is limited by the diameter of the laser beam, which is typically 0.25 to 0.50 mm. Furthermore, in an additional step, the powder is deposited and leveled by a rolling brush which requires other electro-mechanical components. Unfortunately, leveling fine powders with a rolling brush often causes nonhomogeneous packing density. Consequently, an object built from the powder has medium resolution, a non-uniform surface, and often a non-homogeneous structure.
Another conventional method for freeform fabrication involves the use of a three-dimensional (xe2x80x9c3-Dxe2x80x9d) printing process to form xe2x80x9cgreen preformsxe2x80x9d for powdered ceramic and metal applications. See E. Sachs, M. Cima, P. Williams, P. Brancazio and J. Cornie, xe2x80x9cThree-dimensional Printing: Rapid Tooling and Prototypes Directly from a CAD Model,xe2x80x9d ASME J. Eng. Induct., vol. 114, pp. 481-488 (1992). With this method, a silica binder is printed on selected areas of the powder to form a solid cross-section. The process is repeated to form a tack of cross-sections representing the final object. This approach exhibits the same powder deposition problems as selective laser sintering, along with the additional difficulty of removing unbound powder from internal cavities. Furthermore, objects generated by this system are not recyclable.
In addition, conventional 3-D printing, processes are further limited by an inability to automatically remove the media support for over-hangs, large spans, or disjoint areas, and an inability to provide an automated system for physically reproducing three-dimensional computer designs and images. Systems currently available are expensivexe2x80x94the material they use cannot be recycled, and they cannot provide for automated part handling after fabrication due to their use of bulk powders and resins, which require containers rather than conveyor platforms. Accordingly, improvements which overcome any or all of these problems are presently desirable.
Moreover, in addition to the two techniques (SLS and 3-D printing) discussed above, other conventional freeform fabrication schemes include stereo-lithography, shape deposition modeling (xe2x80x9cSDMxe2x80x9d), fused deposition modeling (xe2x80x9cFDMxe2x80x9d), and ballistic particle manufacturing (xe2x80x9cBPMxe2x80x9d). C. W. Hull, U.S. Pat. No. 4,929,402, entitled xe2x80x9cMethod for Production of Three-Dimensional Objects by Stereolithographyxe2x80x9d (1991); F. B. Prinz and L. E. Weiss, U.S. Pat. No. 5,207,371, entitled xe2x80x9cMethod and Apparatus for Fabrication of Three-Dimensional Metal Articles by Weld Deposition,xe2x80x9d (1993); J. R. Fessler et al., xe2x80x9cLaser Deposition of Metals for Shape Deposition Manufacturing,xe2x80x9d Solid Freeform Fabrication Proceedings, pp. 112-120 (University of Texas, Austin 1996); R. S. Crockett, O. J. Kelly, P. D. Calvet, B. D. Fabes, K. Stuffle, P. Creegan and R. Hoffman, xe2x80x9cPredicting and Controlling Resolution and Surface Finish of Ceramic Objects Produced by Stereo deposition Processes, xe2x80x9d Solid Freeform Fabrication Proceedings, pp. 17-24 (University of Texas, Austin 1995); M. E. Orme and E. P. Muntz, U.S. Pat. No. 5,226,948, entitled xe2x80x9cMethod and Apparatus for Droplet Stream Manufacturingxe2x80x9d (1993). These techniques are based on a raster scanning procedure, which is also know as xe2x80x9cpoint-to-pointxe2x80x9d fabrication. P. F. Jacobs, xe2x80x9cRapid Prototyping and Manufacturing Fundamental of Stereolithography,xe2x80x9d pp. 406-411 (Society of Manufacturing Engineering, Dearborn, Mich. 1992) These systems build a single point at a time and consequently only one line or column per scan.
Therefore, a principle object of the present invention is to provide an apparatus and method for manufacturing high quality three-dimensional objects at low cost with minimum setup and run-times.
Another object of the present invention is to provide an apparatus for manufacturing a three-dimensional object utilizing an adjustable planar nozzle for forming a planar jet with uniform thickness.
A further object of the present invention is to provide a high-speed method for manufacturing a three-dimensional object utilizing an adjustable planar nozzle for depositing variable width layers of forming materials.
Yet another object of the present invention is to provide a high-speed method for manufacturing a three-dimensional object utilizing a minimal number of deposition scans per layer of deposited forming materials.
Still another object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a position controllable platform.
Further objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments of the invention.
The present invention relates to an apparatus and method for forming a three-dimensional object which employ planar deposition of molten forming materials on a substrate. In accordance with a preferred embodiment of the present invention the apparatus includes containers for holding the molten forming materials, mechanical members within the containers for pressurizing the molten forming materials through each of the containers, an adjustable planar nozzle mechanism coupled to the containers through which the pressurized molten forming materials flow to form variable size planar jets that are deposited in layers onto the substrate to form the three-dimensional object. Preferably, the adjustable planar nozzle mechanism includes cooperating position controllable plates for forming a variable size planar nozzle opening.
The preferred method of the present invention includes the steps of loading a reservoir of forming materials in one or more containers, heating the forming materials to melt the forming materials in the containers and ejecting the molten forming materials from the containers and through one or more adjustable planar nozzles. In conjunction with the ejecting step, the preferred method further includes the steps of adjusting the size of the adjustable planar nozzles to form variable size planar jets of molten forming materials flowing towards the substrate, positioning the substrate beneath the planar jets, and depositing the forming materials in layers on the substrate to form the three-dimensional object.